update-grub not working -- No medium found

Solution 1:

Solution from this comment on launchpad bug report:

Add a global_filter = [ "r|/dev/sda|", "r|/dev/sdb|" ] to the file /etc/lvm/lvm.conf :

 143         # Example
 144         # Accept every block device:
 145         # filter = [ "a|.*|" ]
 146         # Reject the cdrom drive:
 147         # filter = [ "r|/dev/cdrom|" ]
 148         # Work with just loopback devices, e.g. for testing:
 149         # filter = [ "a|loop|", "r|.*|" ]
 150         # Accept all loop devices and ide drives except hdc:
 151         # filter = [ "a|loop|", "r|/dev/hdc|", "a|/dev/ide|", "r|.*|" ]
 152         # Use anchors to be very specific:
 153         # filter = [ "a|^/dev/hda8$|", "r|.*|" ]
 154         # 
 155         # This configuration option has an automatic default value.
 156         # filter = [ "a|.*|" ]
 157         global_filter = [ "r|/dev/sda|", "r|/dev/sdb|" ]

Run sudo update-grub before filter:

Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
GRUB-Konfigurationsdatei wird erstellt …
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  .
  .
  .
Linux-Abbild gefunden: /boot/vmlinuz-5.4.0-52-generic
initrd-Abbild gefunden: /boot/initrd.img-5.4.0-52-generic
Linux-Abbild gefunden: /boot/vmlinuz-5.4.0-48-generic
initrd-Abbild gefunden: /boot/initrd.img-5.4.0-48-generic
  /dev/sda: open failed: No medium found
  .
  .
  .
Startmenüeintrag für UEFI-Firmware-Einstellungen wird hinzugefügt erledigt

Run sudo update-grub after filter:

Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
GRUB-Konfigurationsdatei wird erstellt …
Linux-Abbild gefunden: /boot/vmlinuz-5.4.0-52-generic
initrd-Abbild gefunden: /boot/initrd.img-5.4.0-52-generic
Linux-Abbild gefunden: /boot/vmlinuz-5.4.0-48-generic
initrd-Abbild gefunden: /boot/initrd.img-5.4.0-48-generic
Startmenüeintrag für UEFI-Firmware-Einstellungen wird hinzugefügt erledigt